Why not use Mopar valves?

[jeep7081]

Stock jeep 4.0 valves are, 1.91" dia, valve length 4.912", Stem dia .312", single grooved (not confirmed)

Why not use Mopar valves from magnum? Too long?

Valve Head Diameter (in):1.970 in.
Valve Head Diameter (mm):50.038mm
Undercut Stem:No
Swirl-Polished:Yes
Overall Valve Length (in):4.910 in.
Overall Valve Length (mm):124.714mm
Valve Stem Diameter (in):0.315 in.
Valve Stem Diameter (mm):8.001mm
Valve Material:Stainless steel
Lock Groove Quantity:1-groove
Lock Groove Style:Conventional
Quantity:Sold individually.

[Cheromaniac]

The Mopar valves CAN be used but there are two main reasons why they're not. Firstly, there's little to gain from using oversize valves in the Jeep 4.0 head. Secondly, LS1 valves and valve springs are much cheaper and have become a more popular choice.

[jeep7081]

Not worth doing the bigger valves then huh? Why everyone doing it then? Sheep?

[Cheromaniac]

Not worth doing the bigger valves then huh? Why everyone doing it then? Sheep?

Bah!

[jeep7081]

Anyone else with an input? I was hoping this forum wasn't all show and no tell (help).

Thanks

[SilverXJ]

What else do you want? Mopar valves are over priced to begin with. If you are talking some other valve like from SI valves, then it wouldn't be a bad idea. Just don't get crazy with an over sized head as larger valves don't help flow due to cylinder and combustion chamber valve shrouding. I am using SI stainless and swirl polished on my intake valves, but only a tiny bit larger than stock.

[jeep7081]

Not sure how to read that.

Anyway, sounds like larger valves only come into play above 4000 rpm's from my reading. I didn't buy the jeep to race. So, might pass.

[SilverXJ]

There isn't that much to read.

4000 or not, there is no benefit to larger valves in the Jeep engine due to cylinder and combustion chamber shrouding. Hesco doesn't even sell larger valves in its aluminum head.

I went with the SI SEV-3954 swirl polished stainless intake Magnum valves. Those valves are 1.92" vs the 1.915" stock size. Not much to even sneeze about. I went with them because they are stainless and swirl polishes. I also added a 30* back cut.

[jeep7081]

Internet posts are hard to read tone.

Fair enough. Sounds like Ill stick with cam and some roller rockers.

[I6FAN]

larger valves don't help flow due to cylinder and combustion chamber valve shrouding

x2...I think I saw a post on HESCO's site that said those were the absolute largest valves to use (with little gained), and going up in size, beyond those, gave diminishing returns unless you offset the valves in towards the cylinder's center which unshrouds them. For the rpm operating range of a jeep engine, the stock valves are about optimum. Some have gotten real good flow numbers with larger valves, but it's not only about quantity of flow, but quality as well; i.e. cleaned up ports and good valve job.

[jeep7081]

Since i have a cam "231" stick with roller rockers 1.6 correct?
http://www.ebay.com/itm/Yella-Terra-Rol ... d3&vxp=mtr